reaper.go

package dontfearthereaper

import "syscall"

// PR_SET_CHILD_SUBREAPER
const prSetSubreaper = 0x36

func init() {
	if _, _, err := syscall.RawSyscall(syscall.SYS_PRCTL, prSetSubreaper, 0, 0); err != 0 {
		panic(err)
	}
}

type Reaper interface {
	Reap() ([]int, error)
}

func New() Reaper {
	return &linuxReaper{}
}

type linuxReaper struct {
}

func (l *linuxReaper) Reap() ([]int, error) {
	return l.reapPids()
}

func (l *linuxReaper) reapPids() ([]int, error) {
	var (
		ws   syscall.WaitStatus
		rus  syscall.Rusage
		pids []int
	)
	for {
		pid, err := syscall.Wait4(-1, &ws, syscall.WNOHANG, &rus)
		if err != nil {
			if err == syscall.ECHILD {
				return pids, nil
			}
			return nil, err
		}
		if pid <= 0 {
			return pids, nil
		}
		pids = append(pids, pid)
	}
}